Visualization of the 12th Cranial Nerve with MRI: Value of Balanced Fast-Field Echo and 3D-Drive Sequences Among the T2 TSE Post-Contrast T1 Sequences

Our aim was to optimize the most effective MR imaging sequence for visualization of the 12th cranial nerve (hypoglossal nerve) through its cisternal course.We applied balanced fast-field echo (B-FFE), 3D-T2 weighted Driven Equilibrium RF Reset Pulse (DRIVE), T2 weighted 2D TSE and post-contrast T1 weighted sequences and tried to find out the best sequence for the perfect visualization of the 12th cranial nerve. One-hundred patients without any hypoglossal nerve paralysis were examined via these sequences. Imaging analysis was graded as follows: certain visualization of nerves (score 2), partially visualized nerves (score 1), non-visualized nerves (score 0).The hypoglossal nerve was visualized exactly in only eight cases and partially depicted in only six cases with the post-contrast T1 series. In B-FFE sequence; 56% of the nerves were properly seen and 8% of the nerves were partially identified, using T2 weighted DRIVE sequences; 30% of the nerves were clearly visualized, the nerves were partially depicted in 15 patients. Regarding the T2 weighted TSE sequence, 15% of the nerves were certainly depicted and in seven patients the nerves were partially depicted.The most diagnostic sequence for the exact visualization of the cisternal course of hypoglossal nerve is B-FFE revealing a 64% visualization rate for the cisternal parts (112 exactly, 16 partially). T2W DRIVE sequence is shown to be more diagnostic than the T2W TSE for vi-sualization of the cisternal part of the hypoglossal nerve.